The invention relates to plasticizer-containing polyvinylbutyrals (PVB) which are suitable for the production of elastic interlayer films with improved adhesion-reducing properties for laminated glass panes of siliceous glass and can advantageously be used for the production of laminated glass. They comprise, as adhesion-reducing additives, active amounts of salts of metals of groups Ia, IIa, IIb and IIIa of the periodic table of the elements and naturally occurring resin acids or derivatives of resin acids, and, if appropriate, customary stabilizers and auxiliaries. They can be shaped thermoplastically by customary methods and are preferably suitable for the production of plasticized PVB films which have advantageously improved adhesion-reducing properties with respect to siliceous glass panes.